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Affordable 3-D printing is still young; just a few years ago, it would have been nearly impossible to have an arbitrary three-dimensional piece of plastic (or resin, or sometimes metal) created from a software description in a box that fits on your desk. But in the several years the printing of *things* has moved fromquaint, quixotic, futzing-about hobby into something that works (fairly) reliably in ever more garages, schools, and hackerspaces, it's gotten good enough that you can now download and print quite a few objects that are available for download, or scan small items to replicate, or scan your friends to print out as statuettes. However, for the most part, these printed pieces are static, and finished. With care, you can print things like a chain, or even a ball joint, but you're still limited mostly to one basic material at a time. (Printing with multiple colors is getting easier, though.) If you want to print a flashlight or a robot, you'll need to add wires and other circuitry as a separate step. That's what the folks at Rabbit Proto (get it?) are trying to change. With the system they're working on, a filament printer is used to fabricate the object itself, but at the same time, both capacitive and conductive features can be baked -- or rather printed -- right in, with a separate print head. We talked with Alexandre Jais and Manal Dia of Rabbit Proto about how the system works, and why you might want to use it. (Alternate video link.)

Tim:
Manal and Alex, I want you to talk to me about Rabbit Proto, and
what it is.Why do you call it that?

Manal:
Great question.So initially Rabbit Proto came from ‘rapid
prototyping’, and it is sort of a word play on that. We started
thinking about Rabbit Proto as a prototyping platform.The
project came out of a class of a year-long design class here at
Stanford that Alex took last year.Maybe you want to talk
about the origins of that?

Alex:
Yeah.Absolutely. It was a class where we were basically
trying to design a platform for innovation where we would use
electronic inks, conductive inks or functional inks.We came
up with this idea of having a physical prototyping platform. 3D
printers came naturally after that. We noticed that people had sort
of an urge to get this kind of device. Because consumer devices and
the prototyping of those consumer devices integrating printed
electronics seemed to be something that was more and more and more
important for a bunch of people. At the end of the year, the project
was presented.And I decided to take it on as more of a
personal project after that.That’s where Rabbit Proto
comes from.And there is another fun story, that originally
when I presented the project, I wanted to print a rabbit with glowing
eyes with a printed circuit inside and small LEDs bringing the
current or bringing light to get the eyes glowing.That’s
where the rabbit comes from as well.

Manal:
Because the rabbit is a very traditional object to be printed to
calibrate a 3D printer.

Tim:
So with the Rabbit Proto system, what you are doing is you are adding
both capacitive and conductive abilities to existing 3D printers.So that means essentially an object can do if this is correct
sort of as its own batteries as well, by adding both of those things
in there.

Alex:
So let me just clarify this in that case.So what we are
doing is that we have a 3D printer add-on that can be adapted on an
open source machine that allows you to deposit both a plastic
filament, but most importantly a conductive paste in our case, and
that conductive paste is great at doing at what you call capacitive
touch sensing.So it is not exactly having a capacitor inside
your object, but when you link it to a micro controller or some sort
of measuring device you can actually form a virtual component by
touching the trace—you can do capacitive touch sensing;
however, there is research at Stanford’s lab and other places
that is looking at printed batteries or printed capacitors other
kinds of functional materials that could do that.So that
might be a vision in three, five, or ten years.

Tim:
Your vision does include printing nearly everything though.I
notice that you have one demo of using peanut butter, so anything
that has the right consistency?

Alex:
Yeah.

Manal:
For us, Rabbit Proto is not only printing circuits inside of
plastic but really kind of opening up 3D printing to printing other
kinds of material, and printing materials that don’t only come
in the form of a filament but materials that come in viscous or
liquid form.And that’s why the extruder and the add-on
that we have designed have this capability of depositing not only the
plastic filament that traditionally gets 3D printed, but also liquid
electric ink, peanut butter and exploring the range of these
different materials.Thinking about applications that we could
print with Rabbit Proto is really the next step for us.The
powerful applications that we have come up with which include a
remote controller, we have made styluses and we are also now thinking
of more interesting artistic interfaces.So all of this is
really the tip of the iceberg in terms of what becomes available.
Again the power of Rabbit Proto is that not only these new materials
but also thinking of going from the pads of one design on a computer
to the actual printed thing.Right now, this is a first
generation product and what it enables is to prototype, and prototype
faster.And making the iterative process of prototyping and
going through multiple iterations of the product that you are
prototyping just much faster, much more integrated asa
process.So you can design your object, print it out, realize
that maybe the buttons need to be bigger or maybe the shape needs to
be different, and rather than going through again the painful steps
of making the plastic, making the circuits—and that usually
takes many days and involves multiples parties, you can just print
that with one button, one printing button basically.

Alex:
Yeah.

Tim:
What sort of printers does your add-on work it? Since you have got
both as an add-on and as a complete printer, as possibilities,I
noticed some pictures of some Delta Box and some RepRap looking ones.Talk about how flexible that is.

Alex:
Absolutely.So the good thing with RepRap is that most of
the parts are available open source, and if you want to modify your
carriage that has the print head moving on it—it is possible,
and the only requirement right now is that your electronic board that
controls the stepper motors for the extrusion is available to welcome
a print head for a plastic object anda stepper motor for the
conductive paste extrusion.After that, right now, we have
noticed that on all the RepRaps that we have seen here, and I think
that the variety of RepRaps as well, there is a hole on the carriage
that what decides pretty standard to adapt extruders, so right now we
have designed it for this.

Tim:
What about the actual conductive material?Is that a mix that
you have come up with to have the right consistency? Or is that an
off-the-shelf product?

Manal:
So we have started with two different materials.The
product that we are using right now is graphite ink, and the reason
we are testing with that, is that it is cheap enough to be used in
our prototyping process, but also conductive so it works well with
our sensing applications.And it is nontoxic and sort of easy
and fun to play with.

Tim:
Now, you are raising a question for me about the interface
between an object that you create that has these internally printed
conductive parts—when you want to connect that to an USB port
or an Arduino board or anything else that you might have as an
adjunct to the actual object—what is the actual interface there
between your printed object and external devices, external things?

Manal:
This is something that has a little logo that we made to showcase
our logo mostly.The process right now is this is connected to
an Arduino Yun.

Alex:
And this was for the game controller, the IC circuits that you
would then you can connect the computer on two.

Manal:
And then this plugs into the USB of a computer.

Tim:
How does the speed compare of printing an object with the embedded
conductive circuitry—is it much slower? Is it the same speed as
if you were printing it full stop on the same kind of filament based
printer?

Alex:
The speed of printing the conductive trace versus the speed of
printing the plastic trace?

Tim:
Yeah, since you are embedding the conductive traces, is it a very
much slower process than if you weren’t—if you were just
printing the object without those traces?

Alex:
Not really, in fact, it is right now, to be perfectly honest,
inside the software, both speeds are set up at the same rate, in our
plastic objects the way that we accelerate it is by saying: I want my
object to be 20% emptier or something like that.In our case,
that would be the difference in terms of speed between the conductive
material and the plastic object.

Tim:
Let me ask you a little bit about licensing too, because you’ve
made a point that this is an open source project. Can you talk about
in what way people can either take advantage of some of the ideas
that you have come up with, or possibly contribute to making things
better? Do you have a Git repository? Or are your objects on
Thingiverse? Is there anything that people can do to take part and
sort of experience this?

Manal: Yes, so we do have a GitHub repository. This project
started on open source 3D printers and so a lot of our development
has been about benefiting from 3D printers that are open source, and
we want to give back to the community and we also want to build a
community around our product.

Stereolithography machines existed, but they were like the Mitsubishi's Avance-25 (both a sinterer, and a CNC mill), well out of the reach of the average person, so the ideas really didn't come around until more people had experience with this technology.

One of the more notable advances I'm seeing is using 3D printing with dissolvable filament in the same way that lost wax castings are done. Make a figure with sprues, embed it in a mold, use a solvent to get the filament out, pour in silver/bronze/metal of choice, let cool, crack the mold off and grind off the sprues, done. This won't make extremely detailed pieces or pieces with a heavy temper (i.e. no 1911 gun parts), but it would make some usable items in metal.

CNC mills are far more limited in the arbitrariness of the shape that can be formed. They cannot form internal corners, complex cavities, overhangs, etc. They are also much more expensive and require far more skill and experience to use. On the other hand, even a home user can make aluminum or stainless steel parts with a desktop mill such as a Sherline [sherline.com]. Mills and 3D printers are really complimentary rather than competitors. I will sometimes do a plastic rapid prototype on a 3D printer, and after check

No. This is what I was trying to say: A mill is more limited in the shapes it can form, but it is less limited in the materials it can use. A home user can use a mill to make parts out of aluminum, brass, or stainless steel. A home user cannot do that with a 3D printer (yet). I only mentioned the Sherline because it is one of the smallest and most affordable mills, while still being a very capable machine.

That word "makers" needs to die now and hard. What about all the countless people who made things with their own hands with more effort than it took to download a CAD file and click print? Bloody poseurs and dilettantes, the lot of them.

Anyone familiar with the physics of electrets? I was thinking a while back that you could freeze a charge in cooling PLA or other plastic being used for printing. I looked around and some guys talked about it briefly a few years ago but never really explored it.

It seems like it might come in handy to bake electrets into your design. If nothing else, you could make half of a position sensor without having to glue on a magnet or something. I seem to remember hearing that the electret effect is influenced

Can't be repaired, and when the DRM is literally printed right in to the device, will 'owning' your purchased product really mean anything in the future?

On the one hand, proprietary product designers will have their customers locked in like never before, and on the other, it seems like you'll have the option to create your own product to order exactly how you like it, especially if you can leverage an open design.

just a few years ago, it would have been nearly impossible to have an arbitrary three-dimensional piece of plastic (or resin, or sometimes metal) created from a software description in a box that fits on your desk.

err, Makerbot is over 4 years old nowPonoko were selling RepRap parts 6 years ago